You've probably got a huge problem on your hands if you've got cracks in your foundation that are growing. If there are trees near the house that are mature, the roots have probably grown into the foundation, and are splitting it. You need to hire a structural engineer to evaluate that before you do anything on your remodel.

I agree, it is definitely time to hire a structural engineer. That person can tell you if you have a serious problem or not.

All concrete cracks. How serious it might be will depend on context. Hire an expert.

i have the same dog as you!! dying to know what you think he is!!! Mine is 15!!

All concrete cracks. The question becomes, "Are the cracks normal/acceptable or are they a sign of serious problems?" To help us with that, you will need to take some photos to show us what you mean by "cracks".

If you are gravely concerned, you can bring in a concrete slab expert from your area to have them assess the situation. In a garage, these normally don't come into play. If you are planning on renovating the garage to create a living space, you will need to do some work to the slab no matter what the cracks look like.

If the space will remain a garage, there is not much to worry about at this point.